The present invention relates to a multi-standard vectorscope for composite video signals. In particular, the present invention is for working with standard PAL and NTSC video signals.
The PAL (Phase Alternation Line) standard pertains to a color television system in which the V component of subcarrier derived from a color burst is inverted in phase from one line to the next in order to minimize hue errors that may occur in color transmission.
The NTSC (National Television System Committee) standard is a standard which was named after an all-industry engineering group which developed U.S. color television specifications. The NTSC standard now describes the American system of color telecasting.
There are three PAL and one NTSC standards with different subcarrier frequencies. In the prior art, two or more different pieces of equipment are required to monitor PAL and NTSC color information, each of which includes a separate oscillator. It has not been practical in the past to combine the different pieces of equipment due to potential crosstalk of the oscillators and the lack of stable DC controlled phase shifter and demodulator that are not frequency sensitive.